I finally saw this movie, via Amazon, when the price finally dropped into the realm of reasonableness. (Do people really pay $12.99 and above to watch a non-Prime Amazon movie?)
Inside all the fantastic photography and sympathetic characters and competent acting, the producers tuck a climate change theme. The aliens who climb out of the Pacific Rim and wreck havoc on the West Coast, are aliens who, millennia before, introduced the dinosaurs to our planet as a sort of guinea pig species. Those creatures died out, however, because the atmosphere was not toxic enough. So the aliens waited until humans polluted it to the extent that Earth is ready for them. So here they come.
On the other hand, humans and their technology defeat the aliens in Act 3, using a nuclear device.
So what's the moral here? Are humans and their polluting technology bad or are they good? Or do we have a mixed bag? Or are the creators of the movie just sloppy or cynical? I vote for sloppy.
Maybe we will find out in the inevitable sequel. I sure hope del Toro is doing it.